One of the reasons I've heard for not having a blog is: "I can barely keep up with my monthly newsletter, how would I ever manage a blog?"
Here are two ways that posting to your blog 2-5 times per month will actually make your monthly newsletter easier:
1. Your content will already be done. It's no longer a big production to write a mind-blowing newsletter article, because you'll be writing content all through the month. You can choose your best post and feature it in the newsletter, or you can present a short introduction (with a link) to all of your new posts and let your readers choose.
2. You'll be a writing machine. It's no longer a struggle to get started when it's time to write for your newsletter, because you'll be constantly in the flow of the writing process. You'll be running on momentum, not climbing a whole mountain and then starting from the bottom again the next month.
Writing is a skill like any other – the more you do it, the easier it gets. You may even start to enjoy it!
(Here are more tips on making the shift from newsletter to blog.)